FIG. 1 depicts a conventional method 10 for providing a magnetoresistive element using a conventional undercut bilayer mask. The layers of the magnetoresistive element are provided, via step 12. Typically, step 12 includes sputter depositing the layers for a spin valve or other analogous giant magnetoresistive (GMR) element. A capping layer for the magnetic element may also be provided, via step 14. For example, Ta or DLC might be used. A bilayer mask is provided on the device, via step 16. The bilayer mask has an undercut at the edges of the mask. The magnetic element is defined, via step 18. Consequently, portions of the layers for the magnetoresistive element exposed by the bilayer mask are removed. Hard bias layers may then be deposited, via step 20. A lift-off may be performed, via step 22. The lift-off removes the bilayer mask. A capping layer, such as Ta, and leads may be provided, via step 24.
Although the conventional method 10 functions at lower densities, issues arise for higher densities. The bottom layer of the bilayer mask has a smaller width, or critical dimension, than the upper layer. Consequently, as discussed above, the bilayer mask is undercut. However, at smaller critical dimensions on the order of 0.06-0.08 μm or less, significant issues are encountered. In particular, the bilayer mask tends to collapse. In addition, the track width becomes difficult to control. Consequently, yield is reduced.
Accordingly, what is needed is an improved system and method for providing an magnetoresistive device, particularly which may be suitable for higher memory densities.